The invention proceeds from a roller pincher for setting the regulation cross-section of a flexible tubing which is inserted into the roller pincher and which may be connected to a medical fluid container, wherein the roller pincher comprises an elongate pinch housing u-shaped in cross-section with two sidewalls and with a web wall connecting these, as well as a pinch roller which acts on the flexible tubing positioned in the housing and is arranged longitudinally displaceable in these sidewalls, with an annular notch on its one circumferential corner region for forming the regulation cross-section of the flexible tubing in cooperation of the pinch housing.
The flow cross-section of the flexible tubing may be changed with the help of such a roller pincher by displacing the pinch roller in the pinch housing, and one may thus set the through-flow quantity of a fluid medium.
Such a roller pincher is described in DE 37 38 965 C1. This roller pincher consists of an elongate, U-shaped housing and of a pinch roller displaceable therein guided in the longitudinal direction. The pinch roller at its one circumferential corner region has an annular notch for accommodating an angularly bent longitudinal edge region of the flexible tubing pinched unmovable in position between the pinch roller and the web of the housing, wherein the annular notch, with the sidewall of the pinch housing lying opposite it forms the respective regulating region of the pinch housing. The sidewall is provided with a projecting means in the form of a slanted running ledge for co-setting the regulation cross-section of the flexible tubing so that the regulation cross-section of the flexible tubing is increased or reduced by displacing the roller pincher in the pinch housing.
This roller pincher has proven itself in practice, i.e. the respectively set regulation cross-section remains essentially constant. Since however the material of the used flexible tubing may vary in softness, with relatively soft flexible tubing material there exists the danger that with the return displacement of the pinch roller, i.e. if the regulation cross-section of the flexible tubing is to be enlarged or if with the exact setting of the regulation cross-section a return movement of the pinch roller is effected, flexible tubing material in the upper region of the ledge-like setting means is rigidly pinched. The result of this it that in such a case the desired regulation cross-section of the flexible tubing may not be precisely set and/or that the flexible tubing is damaged along the adjustment, or setting, length of its regulation cross-section in the pinch housing.
A further roller pincher is known from DE 22 42 539 C2. On a longitudinal edge of the web of the pinch housing it is provided with a channel-like relief tapering in particular in width, which has such a depth that the section of this flexible tubing forming the regulation cross-section of the flexible tubing given bending at an angle may be freely jammed into the respective cross-section location of the relief. The cross-section of the relief changes continuously in the longitudinal direction so that the corresponding regulation cross-section of the flexible tubing may be set on displacement of the pinch roller. On the other longitudinal edge region of the housing web which faces away from the channel-like relief there is provided a fixing prominence which retains the flexible tubing which is pinched between the pinch roller and the web and which may not be flown through at this location, in a manner in which it fixed on all sides. By way of this design the flexible tubing may not be optimally set for achieving an exact and constant regulation cross-section along the regulation length of the pinch housing.